• by Gavin O'Malley  @mp_gavin, April 9, 2012

Online advertising hit $84.8 billion in 2011, representing a 16% year-over-year increase, and accounting for more than 17% of all global measured ad expenditures, according to GroupM. Across global regions, North America led in terms of overall digital ad spending with an estimated $34.5 billion.

The Asia-Pacific region came in second with $24.8 billion, followed by Western Europe with $21 billion, according to the study “This Year, Next Year: Interaction 2012.”

This year, GroupM predicts digital ad spending to reach $98.2 billion globally, representing a nearly 16% increase year-over-year, while the figure represents almost 19% of all measured advertising investment. 

In the 2012 forecast, North America once again ranks first with an estimated $38 billion in digital ad spend, followed by the Asia-Pacific region with $31.4 billion, and Western Europe with $23 billion.

In the U.S., digital ad spending hit $32.2 billion in 2011 -- representing a 22% share of the overall domestic market, and a 12% increase over the previous year, according to the study. This year, those figures are expected to reach $35.4 billion for a 23% share and a 10% increase over 2011.

According to Rob Norman, GroupM Interaction Global CEO, it’s less about the new than what marketers are doing with existing resources. “It seems that less is brand new and that a combination of scale of usage of an increasingly social and mobile Web, the penetration of devices supported by it, and the continued atomization of audiences and content, in both their creation and distribution combine to tell the story of the year.”

GroupM also found that digital advertising’s share of total ad investment rose from 4.4% worldwide in 2004 to a projected 18.8% in 2012. 

Also of note, the average percentage of consumers’ “media time” spent online increased from 11% in 2006 to 19% in 2011, while the absolute number of broadband homes worldwide has nearly tripled in this period to reach 500 million, and the typical country has seen broadband penetration grow by half.

Aside from general monetary inflation, ad investment growth has two main vectors: aggregate audience hours and advertising intensity per individual, according to GroupM.

Average online advertising investment per online user doubled between 2006 and 2011, while for the year, Norway had the highest per-capita online ad investment in the study’s sample: $200.

GroupM points out that e-commerce now accounts for about 5% of global retail sales, with instant-on devices, secure and simple payment, vouchering, and the optimization of retail for mobile serving as catalysts for growth.